def demo(num_list):
    print("函数内部的代码")
    # 使用方法修改列表的内容
    num_list.append(9)
    print(num_list)  # [1, 2, 3, 9]
    print("函数执行完成")


gl_num_list = [1, 2, 3]

demo(gl_num_list)

print(gl_num_list)  # [1, 2, 3, 9]
